// Listing 16.1 The String Class
#include <iostream>
#include <string.h>
using namespace std;

class String
{
    public:
        // constructors
        String();
        String(const char *const);
        String(const String &);
        ~String();

        // overloaded operators
        char& operator[](int offset);
        String operator[](int offset) const;
        String operator+(const String&);
        void operator+=(const String&);
        String& operator=(const String&);

        // General accessors
        int GetLen() const { return itsLen; };
        const char* GetString() const { return itsString; };
        // static int ConstructorCount;
    private:
        String (int);    // private constructor
        char *itsString;
        unsigned short itsLen;
};

// default constructor creates string of 0 bytes
String::String()
{
    itsString = new char[1];
    itsString[0] = '\0';
    itsLen = 0;
    // cout << "\tDefault string constructor\n";
    // ConstructorCount++;
}

// private (helper) constructor, used only by
// class methods for creating a new string of 
// required size, Null filled.
String::String(int len)
{
    itsString = new char[len + 1];
    for(int i = 0; i < len; i++)
    {
        itsString[i] = '\0';
    }
    itsLen = len;
    // cout << "\tString(int) constructor\n";
    // ConstructorCount++;
}

// Converts a character array to a String
String::String(const char* const cString)
{
    itsLen = strlen(cString);
    itsString = new char[itsLen + 1];
    for(int i = 0; i < itsLen; i++)
    {
        itsString[i] = cString[i];
    }
    itsString[itsLen] = '\0';
    // cout << "\tString(char*) constructor\n";
    // ConstructorCount++;
}

// copy constructor
String::String(const String& rhs)
{
    itsLen = rhs.GetLen();
    itsString = new char[itsLen + 1];
    for(int i = 0; i < itsLen; i++)
    {
        itsString[i] = rhs[i];
    }

    itsString[itsLen] = '\0'; 
    // cout << "\tString(String&) constructor\n";
}

// destructor, frees allocated memory
String::~String()
{
    delete[] itsString;
    itsLen = 0;
    // cout << "\tString destructor\n";
}

// operator equals, frees existing memory
// then copies string and size
String& String::operator=(const String& rhs)
{
    if(this == &rhs)
    {
        return *this;
    }

    delete[] itsString;
    itsLen = rhs.GetLen();
    itsString = new char[itsLen + 1];
    for(int i = 0; i < itsLen; i++)
    {
        itsString[i] = rhs[i];
    }

    itsString[itsLen] = '\0';
    return *this;
    // cout << "\tString operator=\n";
}

// non constant offset operator, returns
// references to character so ti can be
// changed!

char& String::operator[](int offset)
{
    if(offset > itsLen)
    {
        return itsString[itsLen - 1];
    }
    else
    {
        return itsString[offset];
}

// constant offset, operator for use
// on const objects (see copy constructor!)
char String::operator[](int offset) const
{
    if(offset > itsLen)
    {
        return itsString[itsLen - 1];
    }
    else
    {
        return itsString[offset];
    }
}

// creates a new string by adding current
// string to rhs
String String::operator+(const String& rhs)
{
    int totalLen = itsLen + rhs.GetLen();
    String temp[totalLen];
    int i, j;
    for(i = 0; i < itsLen; i++)
    {
        temp[i] = itsString[i];
    }

    for(j = 0; j < rhs.GetLen(); j++)
    {
        temp[i] = rhs[j];
    }

    temp[totalLen] = '\0';
    return temp;
}

// changes current string, returns nothing
void String::operator+=(const String& rhs)
{
    unsigned short rhsLen = rhs.GetLen();
    unsigned short totalLen = itsLen + rhsLen;
    String temp(totalLen):
    int i, j;
    for(i = 0; i < itsLen; i++)
    {
        temp[i] = itsString[i];
    }

    for(j = 0; j < rhs.GetLen(); j++)
    {
        temp[i] = rhs[i - itsLen];
    }

    temp[totalLen] = '\0';
    *this = temp;
}

// int String::ConstructorCount = 0;
